the MDP High Field Dipole Demonstrator Design and Status of the MDP High Field Dipole Demonstrator FCC Week in Berlin, May 29-June 2, 2017 Alexander Zlobin US Magnet Development Program Fermi National Accelerator Laboratory

Outline Magnet design and parameters Magnetic and mechanical analysis Magnet fabrication status Conclusion

Cos-theta 15 T Dipole Demonstrator: design selection Approach: use the available tooling and FNAL fabrication and test infrastructure to reduce the magnet R&D cost and time Coil: 60-mm aperture 4-layer graded cos-theta coil 5 cross-sections studied Mechanical structure: Design 1: SS C-clamps and 20-mm thick SS skin Design 2: Al I-clamps and 12-mm thick SS skin Design 3: 50-mm thick Al shell

MDP High Field Dipole Demonstrator design Coil: 60-mm aperture 4-layer graded coil Wsc = 68 kg/m/aperture Cable: L1-L2: 28 strands, 1 mm RRP150/169 L3-L4: 40 strands, 0.7 mm RRP108/127 SS core Insulation: E-glass tape Mechanical structure: Thin StSt coil-yoke spacer Vertically split iron laminations Aluminum I-clamps 12-mm thick StSt skin thick end plates and StSt rods Cold mass OD<610 mm (VMTF Dewar limit)

Magnet Parameters T=1.9 K 100% SSL 87% SSL

3D magnetic analysis 50% filling factor 100% filling factor Cylindrical cut-out Outer block splits for structural reasons Increased distance for magnetic reasons Peak field is in the straight section Coil end were optimized to take into account structural and magnetic considerations Without the iron cutout, Bpeak in the coil end is 2% higher than in the straight section Removing ~45 mm of the iron yoke around coil ends reduces end Bpeak to the level of the straight section Bpeak

Coil magnetization effect and its correction For selected conductor parameters the peak values of b3=-48 and b5=+8 units @ B~1.4 T. 50-75 deg Geometrical b3=-0.8 and 0.375 mm thick iron strips: 0.4mT<B3< 0.1mT at B>1.4 T B3 range reduction by a factor of 11. LHC MB b3~-7 units LHC MBH b3~-25 units 3 layers of 1 mm SC wires: -0.4mT<B3< 0mT at B>0.7 T B3 range reduction by a factor of 13.

2D mechanical analysis 300K Seqv=133 MPa 4K Seqv=176 MPa 4K+15T Bdes=15 T Seqv=133MPa Seqv=182MPa Seqv=161MPa

Towards 16 T dipole Magnet Bssl>17 T at 1.9K Mechanical limit Bmax~15T Large horizontal force and low radial coil rigidity large horizontal coil deformation stress concentration in L1 midplane (Bmax) presented at IPAC2017

Magnet assembly steps 15 T Dipole Mechanical Design and Analysis February 6, 2017

SC strand and cable Cable parameters Cable development L1-L2: 28 strands, 1 mm RRP150/169 L3-L4: 40 strands, 0.7 mm RRP108/127 0.025 mm by 11 mm SS core Cable development 40-strand outer-layer cable was developed for 11 T Dipole Inner-layer cable: Effect of cable Packing Factor on Ic degradation and RRR Final cable cross-section parameters have been selected – PF~87%, Ic degradation <5%, RRR>100 HT optimization to achieve optimal Jc and RRR Magnet SSL estimated based on the cable test data: 11.05 kA (Bap=15.3 T) at 4.5 K 12.2 kA (Bap=16.7 T) at 1.9 K. Cable fabrication 420 m of 28-strand cable 350 m of 40-strand cable + leftover from the 11 T program RRP-108/127 0.7 mm RRP-150/169 1 mm

Mechanical stricture

Axial support structure

Mechanical Model MM design: iron laminations Al I-clamps coil-yoke shim instrumented “dummy” Al coils (short and full-size) Goals: Test assembly tooling and main components of the mechanical structure Develop coil assembly plan and prestress targets Compare experimental data with the FEA

Coil part design and optimization 4-layer coil, complicated 3D parts End parts have been iteratively designed using the BEND/3D printing process L1/2 and L3/4 practice winding completed with satisfactory results

Coil components L1/2 parts (CERN) Cable and L3/4 parts (FNAL) Traces (LBNL) Real international effort!

Coil fabrication status: L3/4 coil #1 Coil winding Coil curing Preparation to reaction

Summary 15 T dipole demonstrator has been developed and now is being fabricated important MDP milestone, collaboration with LBNL contributions from CERN - great integrated international effort Magnet fabrication status fabricate 4 coils – November 2017 assemble and test MM – June-November 2017 assemble the HFDD model – November 2017-January 2018 model test – February-March 2018 Magnetic and mechanical analysis confirmed soundness of the selected design helped to understand design limitations The work on increasing the nominal field to 16 T with appropriate margin has started